Late Holocene hydroclimatic variability linked to Pacific forcing: evidence from Abbott Lake, coastal central California

Abstract

Abbott Lake (Monterey County, California) is one of only a few natural, permanent lakes located in coastal central California. As a result, it represents an important site for assessing spatiotemporal patterns of past hydroclimatic variability. Combined sedimentologic and isotopic analyses are used to describe 1400 years of hydrologic variability within the lake and its drainage basin. Specifically, changes in sand content, percent total organic matter, and δ18O(G. parvus) values suggest changes in paleo-runoff, depositional environment, and relative δ18O(lake water) values, respectively. Nine AMS 14C dates on discrete organic material provide age control with a basal age estimate of ~2400 cal years BP. However, we focus on the most recent 1400 years where the age model is most robust. The results indicate that coastal central California was relatively dry (less runoff) during the Medieval Climatic Anomaly (MCA) and variably wet (more runoff) during the Little Ice Age (LIA). These results are compared to Zaca Lake (Kirby et al. 2014) and Lake Elsinore (Kirby et al. 2010), both located south of Abbott Lake, and to flood event layers from Santa Barbara Basin (Hendy et al. 2013). All three sites, including SBB’s flood event history, indicate a variably wet LIA and dry MCA; however, the absolute timing of wet and dry episodes is more congruent between Zaca and Elsinore than to Abbott Lake suggesting real spatiotemporal variability along the southern to central California coast. Finally, Abbott Lake is compared to Pacific Decadal Oscillation and Pacific sea surface temperature reconstructions. These comparisons suggest a Pacific-sourced control on late Holocene hydroclimates along coastal central California.